Cargo Scanning System

ABSTRACT

The inspection methods and systems of the present invention are mobile, rapidly deployable, and capable of scanning a wide variety of receptacles cost-effectively and accurately on uneven surfaces. The present invention is directed toward a portable inspection system for generating an image representation of target objects using a radiation source, comprising a mobile vehicle, a detector array physically attached to a movable boom having a proximal end and a distal end. The proximal end is physically attached to the vehicle. The invention also comprises at least one source of radiation. The radiation source is fixedly attached to the distal end of the boom, wherein the image is generated by introducing the target objects in between the radiation source and the detector array, exposing the objects to radiation, and detecting radiation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a continuation of U.S. patent application Ser.No. 10/915,687, which is a continuation-in-part of U.S. patentapplication Ser. No. 10/201,543, entitled “Self-Contained PortableInspection System and Method.

FIELD OF THE INVENTION

The present invention relates generally to a self-contained mobileinspection system and method and, more specifically, to improved methodsand systems for detecting materials concealed within or on apersonnel-driven vehicle. In particular, the present invention isdirected towards methods of using a single boom attached to theself-contained mobile inspection system, capable of receiving anddeploying the boom, enabling facile deployment, rigidity and improvedalignment of source and detectors, and a smaller exclusion zone.

BACKGROUND OF THE INVENTION

X-ray systems are used for medical, industrial and security inspectionpurposes because they can cost-effectively generate images of internalspaces not visible to the human eye. Materials exposed to X-rayradiation absorb differing amounts of X-ray radiation and, therefore,attenuate an X-ray beam to varying degrees, resulting in a transmittedlevel of radiation that is characteristic of the material. Theattenuated radiation can be used to generate a useful depiction of thecontents of the irradiated object. A typical single energy X-rayconfiguration used in security inspection equipment may have afan-shaped or scanning X-ray beam that is transmitted through the objectinspected. The absorption of X-rays is measured by detectors after thebeam has passed through the object and an image is produced of itscontents and presented to an operator.

Trade fraud, smuggling and terrorism have increased the need for suchnon-intrusive inspection systems in applications ranging from curbsideinspection of parked vehicles to scanning in congested or high-trafficports because transportation systems, which efficiently provide for themovement of commodities across borders, also provide opportunities forthe inclusion of contraband items such as weapons, explosives, illicitdrugs and precious metals. The term port, while generally accepted asreferring to a seaport, also applies to a land border crossing or anyport of entry.

With an increase in global commerce, port authorities require additionalsea berths and associated container storage space. Additional spacerequirements are typically met by the introduction of higher containerstacks, an expansion of ports along the coastline or by moving inland.However, these scenarios are not typically feasible. Space is generallyin substantial demand and short supply. Existing ports operate under aroutine that is not easily modified without causing disruption to theentire infrastructure of the port. The introduction of new procedures ortechnologies often requires a substantial change in existing portoperating procedures in order to contribute to the port's throughput,efficiency and operability.

With limited space and a need to expand, finding suitable space toaccommodate additional inspection facilities along the normal processroute remains difficult. Additionally, selected locations are notnecessarily permanent enough for port operators to commit to. Moreover,systems incorporating high-energy X-ray sources, or linear accelerators(LINAC), require either a major investment in shielding material(generally in the form of concrete formations or buildings) or the useof exclusion zones (dead space) around the building itself. In eithercase the building footprint is significant depending upon the size ofcargo containers to be inspected.

A relocatable inspection system offers an appropriate solution to theneed for flexible, enhanced inspection capabilities. Because the systemis relocatable and investing in a permanent building in which toaccommodate the equipment is obviated, site allocation becomes less ofan issue and introducing such a system becomes less disruptive. Also, amobile X-ray system provides operators, via higher throughput, with theability to inspect a larger array of cargo, shipments, vehicles, andother containers.

An example of a mobile X-ray inspection system is provided in U.S. Pat.No. 5,692,028 assigned to Heimann Systems. The '028 patent discloses anX-ray examining system comprising a mobile vehicle and an X-rayexamining apparatus for ascertaining contents of an object, saidapparatus including a supporting structure mounted on the mobilevehicle; said supporting structure being portal-shaped for surroundingthe object on top and on opposite sides thereof during X-rayexamination; said supporting structure including (i) a generallyvertical column mounted on said vehicle and rotatable relative to saidvehicle about a generally vertical axis; said column having an upperend; (ii) a generally horizontal beam having opposite first and secondend portions; said beam being attached to said upper end at said firstend portion for rotation with said column as a unit for assuming aninoperative position vertically above said mobile vehicle and anoperative position in which said beam extends laterally from saidvehicle; and (iii) an arm pivotally attached to said second end portionof said beam for assuming an inoperative position in which said armextends parallel to said beam and an operative position in which saidarm extends generally vertically downwardly from said beam; an X-raysource for generating a fan-shaped X-ray beam; said X-ray source beingcarried by said vehicle; and an X-ray detector mounted on saidsupporting structure; said X-ray examining system being adapted totravel along the object to be examined while irradiating the object anddetecting the X-rays after passage thereof through the object.

U.S. Pat. No. 5,764,683 assigned to AS&E discloses a device forinspecting a cargo container, the device comprising: a bed moveablealong a first direction having a horizontal component; a source ofpenetrating radiation, mounted on the bed, for providing a beam; amotorized drive for moving the bed in the first direction; at least onescatter detector mounted on the bed, the at least one scatter detectorhaving a signal output; and a transmission detector for detectionpenetrating radiation transmitted through the cargo container such thatthe beam is caused to traverse the cargo container as the bed is movedand the at least one scatter detector and the transmission detector eachprovide a signal for characterizing the cargo container and any contentsof the cargo container.

U.S. Pat. No. 6,252,929 assigned to AS&E claims a device for inspectinga cargo container with penetrating radiation, the device comprising: abed that is reversibly moveable along a direction having a horizontalcomponent; a source of penetrating radiation, mounted on the bed forproviding a beam having a central axis, the central axis beingpredominantly horizontal; a motorized drive for moving the bed in thefirst direction; at least one scatter detector mounted on the bed, eachscatter detector having a signal output; so that, as the bed is movedforward and backward along the direction, the beam is caused to traversethe cargo container as the bed is moved and each scatter detectorprovides a signal for characterizing the cargo container and anycontents of the cargo container.

U.S. Pat. No. 6,292,533, also assigned to AS&E, claims a system forinspecting a large object with penetrating radiation during motion ofthe system in a scan direction, the system comprising: a vehicle havingwheels and an engine for propelling the vehicle on highways; a boomhaving a proximal end rotatable about a point on the vehicle and adistal end, the boom deployed transversely to the scan direction forstraddling the object during operation of the system; a source ofpenetrating radiation coupled to the vehicle for providing a beam sothat the beam is caused to irradiate a first side of the object as thevehicle is moved in the scan direction; and at least one detectorcoupled to the vehicle on a side of the object opposing the first side,the at least one detector having a signal output, the at least onedetector providing a signal for imaging the object.

U.S. Pat. No. 5,903,623, assigned to AS&E, claims a device, forinspecting a large object with penetrating radiation, the devicecomprising: a self-propelled vehicle capable of on-road travel; a sourceof penetrating radiation, mounted on the vehicle, for providing a beamof penetrating radiation; a beam stop for absorbing the beam ofpenetrating radiation after traversal of the object; and at least onedetector coupled to the vehicle, the at least one detector having asignal output so that the beam is caused to traverse the object in afirst direction as the vehicle is moved and the signal outputcharacterizes the object.

In addition to the features described above, conventional relocatableinspection systems generally comprise at least two booms, wherein oneboom will contain a plurality of detectors and the other boom willcontain at least one X-ray source. The detectors and X-ray source workin unison to scan the cargo on the moving vehicle. In conventionalsingle boom relocatable inspection systems, the X-ray source is locatedon a truck or flatbed and the detectors on a boom structure extendingoutward from the truck.

The aforementioned prior art patents are characterized bymoving-scan-engine systems wherein the source-detector system moves withrespect to a stationary object to be inspected. Also, the detectors andthe source of radiation are either mounted on a moveable bed, boom or avehicle such that they are integrally bound with the vehicle. Thislimits the flexibility of dismantling the entire system for optimumportability and adjustable deployment to accommodate a wide array ofdifferent sized cargo, shipments, vehicles, and other containers. As aresult these systems can be complicated to deploy and pose severaldisadvantages and constraints.

For example, in a moving-scan-engine system the movement of the sourceand detector, relative to a stationary object, may cause lateral twistand lift and fall of the detector or source, due to movement of thescanner over uneven ground, inducing distortions in the scanned imagesand faster wear and tear of the scanner system. Systems where the weightof the detector or source is held on a boom require high structuralstrength for the boom in order to have the boom stable for imagingprocess, thereby adding more weight into the system. Such systems thatrequire a detector-mounted boom to unfold during deployment may cause anunstable shift of the center of gravity of the system off the base,causing the system to tip over. Further, in the case ofmoving-scan-engine systems using a “swing arm” boom approach, the driverdriving the scanner truck is unable to gauge the possibility of hittingthe detector box, mounted on a boom, with a vehicle under inspection(VUI), as the detector box is on the other side of the VUI duringscanning and not visible to the driver.

Additionally, with moving-scan-engine systems, the truck supporting thescanner system is always required to move the full weight of the scannerregardless of the size and load of the VUI, putting greater strain onthe scanning system. Further, because of the integrated nature of priorart systems, swapping detector and radiation systems between scanningsystems is not feasible. In terms of throughput, prior art systems needadditional operational systems that greatly multiply the cost ofoperation to increase the number of VUI to be handled. Alsodisadvantageous in conventional systems is that they suffer from a lackof rigidity, are difficult to implement, and/or have smaller fields ofvision.

Accordingly, there is need for improved inspection methods and systemsbuilt into a fully self-contained, over-the-road-legal vehicle that canbe brought to a site and rapidly deployed for inspection. The improvedmethod and system can, therefore, service multiple inspection sites andset up surprise inspections to thwart contraband traffickers whotypically divert smuggling operations from border crossings that havetough interdiction measures to softer crossings with lesser inspectioncapabilities. Moreover, there is an additional need for methods andsystems that require minimal footprint to perform inspection and thatuse a sufficient range of radiation energy spectrum to encompass safeand effective scanning of light commercial vehicles as well assubstantially loaded 20-foot or 40-foot ISO cargo containers. It isimportant that such scanning is performed without comprising theintegrity of the cargo and should ideally be readily deployable in avariety of environments ranging from airports to ports of entry where asingle-sided inspection mode needs to be used due to congestedenvironments. Such needs are addressed in U.S. patent application Ser.No. 10/201,543, entitled “Self-Contained Portable Inspection System andMethod”, which is herein incorporated by reference in its entirety.

Improved methods and systems are additionally needed to keep therelative position between the radiation source and detector fixed toavoid distortion in images caused by the movement of scanner and/ordetectors over uneven ground or due to unstable structures. In addition,there is a need for improved methods and systems that can providecomprehensive cargo scanning in portable and stationary settings.Specifically, methods and systems are needed in which a single boom isemployed for generating quality images for inspection. Further, thesystem should be mounted on a relocatable vehicle, capable of receivingand deploying the boom.

What is also needed is a single boom cargo scanning system that enablesquick and easy deployment, rigidity and tight alignment of the radiationsource and detectors, and a narrow collimated radiation beam, thusallowing for a smaller exclusion zone. In addition, what is needed is anoptimal scanning system design that allows for the radiation source tobe closer to the Object under Inspection (“OUI”), thereby allowing forhigher penetration capability and complete scanning of the targetvehicle without corner cutoff.

SUMMARY OF THE INVENTION

The inspection methods and systems of the present invention are mobile,rapidly deployable, and capable of scanning a wide variety ofreceptacles cost-effectively and accurately on uneven surfaces. In afirst embodiment, a self-contained inspection system comprises aninspection module that, in a preferred embodiment, is in the form of amobile trailer capable of being towed and transported to its intendedoperating site with the help of a tug-vehicle.

In a second embodiment, the present invention is directed toward aportable inspection system for generating an image representation oftarget objects using a radiation source, comprising a mobile vehicle; adetector array physically attached to a movable boom having a proximalend and a distal end wherein the proximal end is physically attached tothe vehicle; and at least one source of radiation wherein the radiationsource is fixedly attached to the distal end of the boom, wherein theimage is generated by introducing the target objects in between theradiation source and the detector array, exposing the objects toradiation, and detecting radiation. Preferably, the system furthercomprising a hydraulic system located in the vehicle to move the boom.

The system optionally further comprises at least one sensor to determinewhen a target object is positioned between the radiation source and thedetector array. The sensor, upon being activated by the movement of atarget object, transmits a signal to activate said radiation source. Theboom has a main body physically attached to the vehicle, an outer armphysically attached to the main body, and a telescopic arm physicallyattached to the outer arm. The boom has a first configuration and asecond configuration. In the first configuration, the outer arm andtelescopic arm are positioned in substantial parallel horizontalalignment with said vehicle. In the second configuration, the outer armand telescopic arm are positioned in substantial perpendicular alignmentwith said vehicle.

The radiation source can be collimated through an adjustable collimator.The radiation source is aligned with the detector system. The radiationsource is aligned with the detector system using optical triangulationtechniques. The detectors are angled at substantially 90 degreesrelative to a focal point of said radiation source. The detectors arearranged in a dual row. The dual row of detectors are configured in aninterlacing configuration. The data generated by said dual row ofdetectors are subjected to imaging processing. The imaging processingblends images detected by each of said dual rows into a single image.

The present invention is also directed toward a method for inspectingobjects using a portable inspection system that generates an imagerepresentation of a target object using a radiation source, comprisingthe steps of transporting a detector array and at least one source ofradiation to an operation site using a vehicle, wherein the detectorarray is physically attached to a movable boom having a proximal end anda distal end, wherein the proximal end is physically attached to thevehicle, and wherein the radiation source is fixedly attached to thedistal end of the boom; creating a detection region by moving the boominto a substantially perpendicular position relative to the vehicle;moving the vehicle passed the target object such that the target objectpasses through the detection region; activating the radiation source;exposing the target object to radiation emitted from the radiationsource wherein the exposing step results in secondary radiation; anddetecting secondary radiation by the detector array.

Preferably, the motion of the vehicle is substantially constant. Thevehicle comprises a hydraulic system to move said boom. The systempreferably detects when the target object enters the detection region.The boom has a main body physically attached to the vehicle, an outerarm physically attached to the main body, and a telescopic armphysically attached to the outer arm. The boom has a first configurationand a second configuration. In the first configuration, the outer armand telescopic arm are positioned in substantial parallel horizontalalignment with the vehicle. In the second configuration, the outer armand telescopic arm are positioned in substantial perpendicular alignmentwith the vehicle. The radiation source is aligned with the detectorsystem. The radiation source is aligned with the detector system usingoptical triangulation techniques.

The detectors are angled at substantially 90 degrees relative to a focalpoint of the radiation source. The detectors are arranged in a dual row.The dual row of detectors are configured in an interlacingconfiguration. The data generated by said dual row of detectors aresubjected to imaging processing. The image processing blends imagesdetected by each of said dual rows into a single image.

The aforementioned and other embodiments of the present invention shallbe described in greater depth in the drawings and detailed descriptionprovided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will beappreciated, as they become better understood by reference to thefollowing Detailed Description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 provides a perspective view of an exemplary self-containedinspection system of the present invention;

FIG. 2 depicts one embodiment of a hydraulic lift mounted on atug-vehicle and the unloading of a radiation source;

FIG. 3 is a side elevation view of one embodiment of the portableinspection trailer;

FIG. 4 is a side elevation view of one embodiment of the presentinvention in operational mode;

FIG. 5 is a side view of a second embodiment of the present system;

FIG. 6 is a second embodiment of an inspection trailer;

FIG. 7 is one embodiment of an inspection trailer, depicting the use ofa hydraulic system;

FIG. 8 is top plan view of a second embodiment of the present inventionduring operation;

FIG. 9 a is a schematic view of an exemplary hydraulic system used forautomatically unfolding the detector panels;

FIG. 9 b is a second view of an exemplary hydraulic system used forautomatically unfolding the detector panels;

FIG. 10 is a flowchart of one exemplary process for setting-up thesystem of the present invention;

FIG. 11 is a flowchart of one exemplary process for deploying thedetector system;

FIG. 12 is a view of an exemplary radiation source box;

FIG. 13 is a representation of an exemplary embodiment of the integratedsingle boom cargo scanning system of the present invention;

FIG. 14 is a side view illustration of one embodiment of the vehicle ofthe present invention in a “stowed” position;

FIG. 15 is a top view illustration of one embodiment of the vehicle ofthe present invention in a “stowed” and relocatable position;

FIG. 16 is a side perspective view of the single boom cargo scanningtruck of the present invention in a preferred embodiment;

FIG. 17 depicts the top view of the single boom cargo scanning system ofthe present invention, in a deployed position;

FIG. 18 depicts an exemplary movement of the telescopic arm of thesingle boom cargo scanning truck of the present invention;

FIG. 19 depicts a second exemplary movement of the telescopic arm of thesingle boom cargo scanning truck of the present invention;

FIG. 20 is a rear view illustration of the single boom cargo scanningsystem of the present invention, in a preferred usage;

FIG. 21 depicts the rotating collimation wheel employed in the scanningsystem of the present invention;

FIG. 22 illustrates a preferred embodiment of the detector array asemployed in the single boom cargo scanning system of the presentinvention;

FIG. 23 is a detailed illustration of one embodiment of the detectorsemployed in the detector array shown in FIG. 10;

FIG. 24 is a detailed illustration of another embodiment of thedetectors employed in the detector array shown in FIG. 10, where thedetectors are arranged in a dual row;

FIG. 25 is a block diagram of an exemplary display and processing unitof the single boom cargo scanning system of the present invention; and

FIG. 26 is a flowchart depicting the operational steps of the singleboom cargo scanning system of the present invention upon execution of animage generation program.

DETAILED DESCRIPTION OF THE INVENTION

The inspection methods and systems of the present invention are mobile,rapidly deployable, and capable of scanning a wide variety ofreceptacles cost-effectively and accurately, with rigidity, ease of use,and a wider field of vision. Reference will now be made in detail tospecific embodiments of the invention. While the invention will bedescribed in conjunction with specific embodiments, it is not intendedto limit the invention to one embodiment.

In a first embodiment, FIG. 1 shows a perspective view of an exemplaryself-contained inspection system 100. The system 100 comprises of aninspection module 15 that, in a preferred embodiment, is in the form ofa mobile trailer capable of being towed and transported to its intendedoperating site with the help of a tug-vehicle 10. While the presentinvention is depicted as a tug vehicle 10 connected to a trailer 15, oneof ordinary skill in the art would appreciate that the vehicular portionof the system and inspection module portion of the system could beintegrated into a single mobile structure. The preferred embodiment usesa tug vehicle independent from the inspection module because, as laterdiscussed, it adds greater flexibility in how the system is used. Inanother embodiment, the operator trailer, unit 15, could be a separatevehicle by itself.

The tug-vehicle 10 can serve as a support and carrier structure for atleast one source of electromagnetic radiation 11; hydraulic lift system12, such as the Hiab lifting cranes along with suitable jigs andfixtures or any other lifting mechanism known in the art, to load andunload the at least one source 11; and a possible radiation shield plate13 on the back of the driver cabin of tug-vehicle 10, to protect thedriver from first order scatter radiation. The inspection trailer 15 ishitched to the tug-vehicle 10 using a suitable tow or hitch mechanism 5such as class I through V frame-mounted hitches; fifth wheel andgooseneck hitches mounted on the bed of a pick-up; a simplepintle-hitch; branded hitches such as Reese, Pull-rite and Hensley orany other means known to one of ordinary skill in the art. The class ofthe hitch indicates the amount of trailer load that it can handle. Forexample, a class I hitch is rated for a trailer load of about 2000pounds whereas a class V hitch is rated for loads greater than 10,000pounds. A typical manually-releasable tow-bar mechanism, disclosed inU.S. Pat. No. 5,727,806 titled “Utility Tow Bar” and assigned to ReeseProducts Inc., comprises a coupler assembly including a hitch ballreceiving socket and cooperating lock. This facilitates selectiveconnection of a tow-bar to the hitch ball of a trailer hitch receivercarried by a towing vehicle. Alternatively, automatic hitches may alsobe used for quick coupling and detaching of the tow truck and trailerwithout manual intervention or attendance.

Referring back to FIG. 1, the inspection or scanning module 15 iscustom-built as a mobile trailer can provide support for a plurality ofdetector arrays 16 and a boom 17 to deploy a power cable to at least onesource of radiation during operation. The trailer 15 also houses anoperator/analyst cabin including computer and imaging equipment alongwith associated power supplies, air conditioning and power generatingequipment in accordance with the understanding of a person of ordinaryskill in the art of X-ray generation. In high energy/high performancesystem, the trailer containing the detector array 16 and boom 17 may bein a different unit from the trailer housing the operator inspectionroom 15. This will allow the operator to avoid being in a high radiationarea and reduce the amount of shielding required for his protection. Inpreferred embodiment, the trailer 15 may additionally include aplurality of leveling or support feet 18, 19 to enable stabilizedimaging when in stationary use.

In order to use the system 100, the inspection trailer 15 is towed tothe inspection site by the tug-vehicle 10. After positioning theinspection trailer 15, the tug-vehicle 10 is detached and movedsubstantially parallel to the trailer 15 and towards the side carryingthe detector system 16. Here, the radiation source box 11 is shifted outof the tug-vehicle 10 and lowered down to the ground by a hydrauliccrane 12 mounted on the tug-vehicle 10. Thus, the source box 11 isplaced laterally opposite to the detector system 16 at a distance thatis suitable to allow an OUI to pass between the source 11 and detector16 during the scanning process. An OUI could be any type of object,including cars, trucks, vans, mobile pallets with cargo, or any othertype of moveable object. During the scanning process, the tug-vehicle10, after lowering down the source 11, is maneuvered to attach to theOUI and tow the OUI through the radiation scan beam. As the OUI is towedthrough the radiation beam, an image of the OUI is produced on theinspection computers housed within the trailer 15 showing theradiation-induced images of the articles and objects contained withinthe OUI.

Referring to FIG. 2, a rear elevation view of a preferred embodiment ofthe tug-vehicle 10, depicting the unloading of source of radiation 11using a lifting mechanism 12 is shown. As previously mentioned, in apreferred use of the system, the tug vehicle is separated from thetrailer and driven to an area where the source is to be positioned,preferably largely parallel to the trailer and separated from thetrailer by sufficient space to allow an OUI, such as a vehicle orcontainer, to pass.

To allow for the safe and rapid deployment of the radiation source 11, apreferred embodiment uses stabilizing feet 14 to increase the base ofthe tug vehicle 10 and off load the stress from the wheels, as thesource 11 is lifted off the tug-vehicle 10 using a suitable hydrauliclift 12 and brought down from the side for deployment. The radiationsource 11 may be put into position using any means known to one ofordinary skill in the art, such as a wheeled platform. The hydrauliclift 12 puts the source box 11 on a wheeled platform so that the sourcecan now be tugged and can be angularly rotated into a suitable position.

The source of radiation 11 includes radio-isotopic source, an X-ray tubeor any other source known in the art capable of producing beam flux andenergy sufficiently high to direct a beam to traverse the space throughan OUI to detectors at the other side. The choice of source type and itsintensity and energy depends upon the sensitivity of the detectors, theradiographic density of the cargo in the space between the source anddetectors, radiation safety considerations, and operationalrequirements, such as the inspection speed. One of ordinary skill in theart would appreciate how to select a radiation source type, dependingupon his or her inspection requirements. In one embodiment, where theOUI is a large sized container or car that highly attenuates the X-raybeam, the radiation could be from an X-ray tube operating at a voltagein substantial excess of 200 keV, and may operate in a region ofapproximately 4.5 MeV.

A further possibility for examining an OUI can be achieved by drivingthe radiation source 11 with respectively different radiation energiesor by using two detector systems, having varying sensitivities todiffering radiation energies. By comparing at least two congruentradiation images that were obtained with respectively differentradiation energies, it could be possible to discriminate articles havinglow and high ordering number. Organic materials, such as drugs andexplosives, can thus be better distinguished from other materials, forexample metals (weapons).

While the tug vehicle has been moved, with the radiation source, to aposition for the deployment of the radiation source, the inspectiontrailer is also being deployed. Referring now to FIG. 3 a side elevationview of the portable inspection trailer 15 is shown incorporating a boom17 and a plurality of detectors 16 folded to the side of the trailer 15.The detectors 16 are preferably in a formation that, when folded orstored, permit the trailer 15 to safely travel on public roadways.Additionally, the detectors 16 are preferably integrally formed toenable for stable, yet rapid deployment. The detectors may also belinear arrays that extend substantially parallel to the base of thetrailer and, when deployed, extend substantially orthogonal to the baseof the trailer.

In one embodiment, as shown in FIG. 4, the detectors comprise threesections 16 a, 16 b and 16 c that are capable of being folded, asearlier seen in FIG. 3, such that, when in a storage position, thedetectors recess into the side of the inspection trailer 15. By formingdetectors such that they can fold in a storage position, it is possibleto produce a compact trailer 15 that can safely, and legally, travelroadways. When unfolded during operation, the detectors 16 a, b and c,may assume a linear or an arched shape. In one embodiment the detectorsassume an approximate “C” shape, as seen in FIG. 4. The preferred “C”shape allows for a shorter total height of detectors in folded position,minimizes alignment problem because top and bottom sections 16 a, 16 care almost in the same line, provides a relatively smaller dose to alldetectors and are less prone to damage by the effective overall heightof the trailer 15. As shown, the detector sections 16 a, 16 b, and 16 care in alignment with a radiation source 11 that is powered through apower cable 25 attached to a boom 17. Within the area defined betweenthe detector sections 16 a, b, and c and the radiation source 11 is anOUI 20.

In order to facilitate push-button deployment and the dispensing away ofassembling tools or skill, the action of folding or unfolding of thedetectors 16 a, 16 b and 16 c is managed by a suitable hydraulic systemknown to a person of ordinary skill in the art.

FIGS. 6 and 7 show one embodiment of the inspection trailer 15,depicting the use of a typical hydraulic system 22 for deploying anexemplary array of linear-shaped detectors 21. During operation, thehydraulic mechanism 22, pushes the detectors 21 in a substantiallyvertical position while the stabilizing feet 25 and 26 are deployeddownwards so that the trailer 15 now partially rests on them instead ofjust on the wheels, thereby minimizing movement and providing stabilityto the trailer 15 during the scanning operation. A boom 23, is alsoshown in a rest position lying on the top of the trailer 20, and pivotedat one end around a vertical axis 24, such that the boom 23 can rise androtate orthogonally relative to the trailer 15 during deployment.

In one embodiment, as shown in FIG. 4, the detectors 16 remain folded toa side of the trailer 15 in an approximately vertical position so thatthe associated hydraulic mechanism is only used to unfold the foldedsections of the detector system 16. FIGS. 9 a and 9 b show an exemplaryhydraulic system 900 used to unfold the top detector panel 916 a. Thehydraulic system 900 comprises a reversible electrical motor 907 todrive a hydraulic pump 906 that in turn provides hydraulic fluid underpressure to a double acting hydraulic actuator 905 attached to trailer915. When the hydraulic actuator 905 is required to unfold the detector916 a, pressurized hydraulic fluid is pumped into chamber A, engagingpiston 908 to move slider ball 909 that in turn unfolds the detector 916a. Once the detector 916 a is unfolded through an acceptable angle 910the detector 916 a is securely latched in position using a mechanicallatch 920 such as a simple hook and peg system or any other latchingarrangement known to one of ordinary skill in the art. A similararrangement can be used to deploy the lower detector panel.

The detectors 16 may be formed by a stack of crystals that generateanalog signals when X-rays impinge upon them, with the signal strengthproportional to the amount of beam attenuation in the OUI. In oneembodiment, the X-ray beam detector arrangement consists of a lineararray of solid-state detectors of the crystal-diode type. A typicalarrangement uses cadmium tungstate scintillating crystals to absorb theX-rays transmitted through the OUI and to convert the absorbed X-raysinto photons of visible light. Crystals such as bismuth germinate,sodium iodide or other suitable crystals may be alternatively used asknown to a person of ordinary skill in the art. The crystals can bedirectly coupled to a suitable detector, such as a photodiode orphoto-multiplier. The detector photodiodes could be linearly arranged,which through unity-gain devices, provide advantages overphoto-multipliers in terms of operating range, linearity anddetector-to-detector matching. In another embodiment, an area detectoris used as an alternative to linear array detectors. Such an areadetector could be a scintillating strip, such as cesium iodide or othermaterials known in the art, viewed by a suitable camera or opticallycoupled to a charge-coupled device (CCD).

FIG. 8 shows a plan view of the inspection trailer 15, associated imageprocessing and control system 40 and an arrangement of detector system16 as seen from the top. As shown, the plane of the detector system 16represented by axis 35, is kept slightly skewed from the respective sideof the trailer 15 by an angle 36, such as 10°, so that the angle betweenthe trailer 15 and the path of the radiation beam 30 is substantially inexcess of 90°. At angles of about 90° and above, relative to scatterlocation and beam path 30, the magnitude of first order scatterradiation is quite low. In the present system, when radiation is firstemitted, the most likely scatter source is the detector system 16.Therefore the resulting relative angular position, between the axis 35and beam path 30 due to the skew angle of the detector plane 35 from thetrailer 15, helps in protecting driver 37 of the tug-vehicle 20 fromradiations scattered by the detector system 16.

The X-ray image processing and control system 40, in an exemplaryembodiment, comprises a computer and storage systems which records thedetector snapshots and software to merge them together to form an X-rayimage of the vehicle 20 which may further be plotted on a screen or onother media. The X-ray image is viewed or automatically analyzed by OUIacquisition system such as a CRT or monitor that displays the X-rayimage of the vehicle 20 to an operator/analyst. Alternatively, the OUIacquisition systems may be a database of X-ray images of desiredtargets, such as automobiles, bricks or other shapes that can becompared with features in the image. As a result of this imaging, onlyarticles that were not contained in the reference image of the containeror vehicle 20 are selectively displayed to an operator/analyst. Thismakes it easier to locate articles that do not correspond to a referencecondition of the container or vehicle 21, and then to conduct a physicalinspection of those articles. Also, for high-resolution applications,the electronics used to read out the detector signals may typicallyfeature auto-zeroed, double-correlated sampling to achieve ultra-stablezero drift and low-offset-noise data acquisition. Automatic gain rangingmay be used to accommodate the wide attenuation ranges that can beencountered with large containers and vehicles.

Referring now to FIG. 10, during deployment the inspection trailer istransported 1005 to the operation site and towed 1010 in position by thetug-vehicle. The trailer is advantageously positioned proximate to acargo loading area so that the laden cargo containers can pass throughthe source-trailer system without disrupting port activities. One suchpreferable place for positioning the trailer could be an exit point of aport. Another aspect that may influence the decision of positioning thetrailer could be the availability of a large enough area, called the“exclusion zone”, around the scanner system. The exclusion zone is anarea around the scanner in which general public are not authorized toenter due to the possibility of their getting exposed to doses ofradiations scattered during the scanning process. The exclusion area isdependent upon the magnitude of current setting the intensity of theradiation source.

After positioning the trailer suitably, the tug-vehicle is preferablydetached 1015 from the trailer. Next the tug vehicle is moved 1020 to anarea proximate to and preferably parallel from the inspection trailer inorder to unload and position the source of radiation. The source ofradiation is then pulled 1025, or lowered, out of the tug-vehicle, usinga hydraulic lift, and lowered down to the ground to be deployedlaterally opposite to the side of the trailer supporting the detectors.The boom is also rotated 1030 substantially orthogonally from its restposition in order to deploy 1030 control cable to provide power andcontrol signals to the source. The electrical power generator, housed inthe trailer, is now turned on 1035 to provide power to the electricaldevices in the system.

While the generator is deployed described above, the detectors areunfolded 1045. The detectors may be positioned in a variety of ways, asearlier described, including a linear or, using a suitable hydraulicmechanism, in an approximate “C” shape. Shown in FIG. 11 is a processflow diagram of the detector deployment process. Stabilizing feet arefirst deployed 1105 to provide stability to the trailer as it deploysthe detector structure. One of ordinary skill in the art wouldappreciate that the objective of deploying stabilizing feet is to widenthe trailer support base and distribute weight to increase stability andlessen the likelihood of tipping. Other mechanisms could be used tostabilize the trailer structure, including, for example, a hydraulicjack that lifts the trailer up so that the trailer now rests on asupport platform instead of on the wheels; hydraulic brakes that areengaged once the trailer has been suitably positioned such that thebrakes cusp the trailer wheels preventing any movement of the wheels; orsimply a pair of wheel-stops that can be manually placed in front and atthe rear of front and rear wheels respectively preventing anytranslational motion of the wheels.

Once the trailer is stable, the reversible electric motor of thedetector hydraulic system is turned on 1110. The motor starts 1115 thehydraulic pump that fills 1120 the hydraulic actuator with pressurizedhydraulic fluid. This moves 1125 the hydraulic piston, attached to thedetector through a slider ball, causing the detector to unfold 1130upwards. After unfolding the detector panel to a suitable position, thedetector panel is latched 1135 in order to hold it in the requiredunfolded position. A similar process is carried out to unfold the bottompanel of the detector system.

Once the radiation source box is placed opposite to the detector arrayand the array box is fully deployed, alignment 1040 steps are carriedout comprising of: adjusting the vertical height of the radiation sourcebox using leveling mechanisms such as leveling screws or any otherleveling means known to a person of ordinary skill in the art; andalignment of the radiation beam with respect to the detectors.

FIG. 12 is an exemplary embodiment of the radiation source box 11,showing leveling screws 5, 6, 7 and 8 that can be turned to manipulatethe vertical height of the source box 11 and an array of laser pointers9 built into the collimator 10 to facilitate proper alignment of theradiation beam 12 with the detectors. In one embodiment, opticaltriangulation method is used for aligning the plane of the radiationbeam with a predefined “zero” or “idealized centerline” of the detectorsystem. Such optical triangulation techniques, as known to a person ofordinary skill in the art, use a source of light such as a laser pointerto define the radiation beam path. These laser pointers are directed toimpinge on a predefined “zero” of the detectors. The “zero” of thedetectors maybe a spot representing the centroid of the detector systemor an idealized centerline representing a spatial x-y locus of an idealfan beam plane intersecting the plane of the detectors substantiallyorthogonally. In one arrangement, the spatial position of the laserpointers impinging on the detectors is sensed by an array ofphoto-electric diodes of the detector system that send the correspondingposition signals to a computer housed within the trailer. The computercompares the spatial position of the laser pointers with a predefined“zero” of the detector system and sends correction control signals tothe source box through the control cable (attached to the boom) foradjustments till the laser pointers are reasonably lined-up with thedetector system

Depending on conditions, other system elements may be deployed to enablethe screening process. Such elements may include surveillance systemssuch as the closed-circuit television (CCTV) to monitor area around thescanner to control the exclusion zone, a lighting system and a wirelessnetwork. The lighting system may be required to facilitate nightoperation. In a preferred embodiment the analysis of the scanned imagesof an OUI are done by an analyst seated inside the inspection trailer.However, in another embodiment a separate command center mayalternatively or additionally be located away from the scanner,preferably outside the exclusion zone, where a similar analysis ofscanned images may be done. In such an arrangement wireless networks mayadditionally be needed to transfer data from the scanner system to thecommand center.

After deploying the system as described above, an operator may undertakethe following procedure to examine an OUI using the present invention.As used in this description, an OUI is any receptacle for the storage ortransportation of goods, and includes freight pallets as well asvehicles, whether motorized or drawn, such as automobiles, cabs andtruck-trailers, railroad cars or ship-borne containers and furtherincludes the structures and components of the receptacle.

Referring back to FIG. 5, a side elevation view of the system of oneembodiment of the invention during operation is shown. The OUI in thisillustration is a vehicle 20 that is being towed between the source 11and detectors 16 by the tug-vehicle 10. In a preferred arrangement thetug-vehicle 10 is the same vehicle that was earlier used to transportthe inspection trailer 15 to the site. Thus the tug-vehicle 10 servesthe twin purpose of not only transporting the inspection trailer 15 butalso to tow an OUI, such as vehicle 20, during the scanning process toprovide a relative motion between an OUI and the source 11/detector 16system. The mechanism used to attach the tug-vehicle 10 to the trailer15 and then to an OUI during operation may be different. For example,one or more wheel catchers 22 that cups one or more wheels of an OUI,thereby allowing the tug vehicle 10 to pull the OUI by dragging thewheel catcher 22, may be used to tow the inspected vehicle 20.Similarly, other attachment mechanisms may alternatively be used, aswould be known to persons ordinarily skilled in the art.

During the scanning operation, the source 11 and detectors 16 remainstationary and aligned with respect to each other while the OUI, whichis a vehicle 20 in this case, is made to move. In a preferredembodiment, the motion of the vehicle 20 is kept steady and at aconstant velocity such as at or around 2 km/hr. Since, irregularities inthe motion of the vehicle 20 may result in distortions in the scannedimage, the motion is preferably made as regular, even and constant asfeasible using known control systems such as by engaging the tug-vehicle10 in “auto speed” mode. In alternate embodiments, to scan at varyingspeeds depending on the speed of the tug-vehicle 10, irregularities ofmotion are measured and the radiographic image is correspondinglycorrected. To accomplish this, a telemetry mechanism may be used torelay the speed of the tug-vehicle 10 to the inspection trailer 15. Forexample, one or more motion encoders can be affixed to one wheel of thetug-vehicle 10. An encoder measures the rotational velocity of the wheeland transmits a corresponding electrical signal to the imaging system'scomputer housed within the inspection trailer 15. If there is a changein speed, the computer automatically includes a correspondingcompensation in the timing of the detector signals for that location,thereby eliminating image distortions induced due to non-uniform motionof the tug-vehicle 10.

Start-sensors, not shown, are strategically placed to allow an imagingand control system, located within the inspection trailer 15, todetermine that the tug-vehicle 10 has passed the area of beam and thevehicle 20 to be inspected is about to enter the X-ray beam position 30.Thus, as soon as the vehicle 20 to be inspected trips the start-sensors,the radiation source 11 is activated to emit a substantially planarfan-shaped or conical beam 30 (for the duration of the pass) that issuitably collimated for sharpness and made to irradiate substantiallyperpendicular to the path of the vehicle 20.

Since the source 11 and detector 16 remain stationary during thescanning process, collimation can be adjusted to an advantageous minimumsuch that the fan beam emerging out of the collimator just covers thedetectors 16. Apart from using a collimator at the source of radiation,in an alternate embodiment, another collimator arrangement can beadditionally provided integral to the detector system 16 so that thewidth of the fan beam finally striking the detectors 16 may be furtherchanged. As known in the art, X-ray scanning operates on the principlethat, as X-rays pass through objects, some get stopped, some passthrough, and some get deflected owing to a number of different physicsphenomena that are indicative of the nature of the material beingscanned. In particular, scattering occurs when the original X-ray hitsan object and is then deflected from its original path through an angle.These scatter radiations are non-directional and proportional to thetotal energy delivered in beam path. A narrowly collimated beam willkeep the overall radiation dose minimal and therefore also reduce theamount of scatter radiation in the area surrounding the scanner. This,in one arrangement, is achieved by using an adjustable collimator with along snout.

Also, the fan angle of the fan beam 30 is wide enough so that theradiation from the source 11 completely covers the cross section of thevehicle 20 from the side and the radiation is incident on theapproximately “C”-shaped radiation detectors 16. It would also bepossible to make the fan angles of the source 11 smaller than would benecessary to encompass the entire cross-section of the articles beinginspected, in which case the source 11 could be mounted so as to bepivotable around an axis that is essentially parallel to the directionof motion of the vehicle 20. Thus, by pivoting the source 11, theentirety of the cross section of the vehicle 20 can be penetrated by theradiation.

At any point in time when the source 11 is on, the detectors 16 aresnapshots of the radiation beam attenuation in the vehicle 20 for aparticular “slice” of the vehicle 20 under inspection. Each slice is abeam density measurement, where the density depends upon beamattenuation through the vehicle 20. The radiation detectors 16 convertthe lateral radiation profile of the vehicle 20 into electrical signalsthat are processed in an image processing system, housed in theinspection trailer 15, while the vehicle 20 is being conducted past thesource 11 and the radiation detector 16.

In a second embodiment, the present invention is directed towards arelocatable cargo inspection system that employs a single boom attachedto a truck that is capable of receiving and deploying the boom. The boomcomprises a plurality of radiation detectors and a source. The boom ispreferably installed in the rear of the truck to minimize radiationdosage to the driver and is capable of being folded into the truck andfolded out, thus forming an inverted “L” on either the driver orpassenger side.

The single boom structure permits the source, positioned at the base ofthe connecting structure, to rigidly align with the detector array, alsopermitting the unit to operate with a narrower beam width and a lowerradiation level. In addition, the position of the source at the base ofthe connecting structure enables a larger field of view relative toconvention systems having the source on the vehicles. The sourcepreferably extends to a height as low as six inches off the ground.Reference will now be made in detail to specific embodiments of theinvention. While the invention will be described in conjunction withspecific embodiments, it is not intended to limit the invention to oneembodiment.

Referring to FIG. 13, the schematic representation of an exemplaryembodiment of the integrated single boom cargo scanning system of thepresent invention is depicted. The self-contained inspection system 1300of the present invention comprises, in a preferred embodiment, aninspection module in the form of a rig/tractor trailer 1301, capable ofbeing driven to its intended operating site. The vehicular portion ofthe system and the inspection module portion of the system areintegrated into a single mobile structure. The integrated modular mobilestructure serves as a support and carrier structure for at least onesource of electromagnetic radiation; and a possible radiation shieldplate on the back of the driver cabin of the vehicle, used to protectthe driver from first order scatter radiation.

The inspection or scanning module 1300 is custom-built as an integratedmobile trailer 1301 and can provide support for a single boom 1302 todeploy a power cable (not shown) to at least one source of radiation1304 during operation. In addition, boom 1302 houses an array ofdetectors 1303. In a preferred embodiment, boom 1302 is attached totrailer 1301, capable of receiving and deploying the boom. Boom 1302 ispreferably installed and located in the back of trailer 1301 to minimizeradiation dosage to driver in trailer cab 1305. Trailer 1301 also housesan operator/analyst cabin including computer and imaging equipment alongwith associated power supplies, air conditioning and power generatingequipment (not shown) in accordance with the understanding of a personof ordinary skill in the art of X-ray generation. Depending onconditions, other system elements may be deployed to enable thescreening process. Such elements may include surveillance systems suchas the closed-circuit television (CCTV) to monitor area around thescanner to control the exclusion zone, a lighting system and a wirelessnetwork. The lighting system may be required to facilitate nightoperation. In a preferred embodiment the analysis of the scanned imagesof an OUI are done by an analyst seated inside the inspection trailer.However, in another embodiment a separate command center mayalternatively or additionally be located away from the scanner,preferably outside the exclusion zone, where a similar analysis ofscanned images may be done. In such an arrangement wireless networks mayadditionally be needed to transfer data from the scanner system to thecommand center. In addition, boom 1302 is capable of being folded intotrailer 1301 in a “stowed” position or folded out from trailer 1301 in a“deployed” position, on either the driver or passenger side.

The radiation source box 1304 is located on the same single boom 1302 asthe detection system 1303. Thus, while source box 1304 is locatedopposite the detector system 1303 at a distance that is suitable toallow Object under Inspection (“OUI”) to pass in the area 1306 betweenthe source 1304 and detector array 1303 during the scanning process, itis located on the same boom 1302 to eliminate the need for alignment.The radiation source, in a preferred embodiment is an X-ray generator.In yet another preferred embodiment, the radiation source is a linearaccelerator (LINAC). If the X-ray generator or LINAC is mounted on thesame single boom as the detector arrays, the need for sophisticatedalignment systems each time the system is deployed is eliminated. Thus,the radiation source and detectors are substantially permanently alignedon the same single boom. The feature also allows for scanning at variousdegrees of offset, again without the need to realign the LINAC or X-raygenerator and detectors.

An OUI could be any type of object, including cars, trucks, vans, cargocontainers, mobile pallets with cargo, or any other type of cargoobject. During the scanning process, the OUI remains in the areademarcated by the deployed boom 1306 as a fixed piece of cargo while theself-contained inspection rig/tractor trailer 1300 moves over the OUI.Alternatively, the self-contained inspection rig/tractor trailer 1300can remain in place while a piece of cargo is driven, moved, dragged,tagged, and/or lifted through the scanning region 1306. As theself-contained inspection trailer 1300 is moved over OUI, an image ofthe OUI is produced on the inspection computers housed within thetrailer showing the radiation-induced images of the articles and objectscontained within the OUI (not shown). Therefore, in a preferredembodiment, the system is designed such that the self-containedinspection trailer moves over the stationary object (OUI).

The source of radiation includes radio-isotopic source, an X-ray tube,LINAC or any other source known in the art capable of producing beamflux and energy sufficiently high to direct a beam to traverse the spacethrough an OUI to detectors at the other side. The choice of source typeand its intensity and energy depends upon the sensitivity of thedetectors, the radiographic density of the cargo in the space betweenthe source and detectors, radiation safety considerations, andoperational requirements, such as the inspection speed. The system ofthe present invention could employ source-based systems, for example,cobalt-60 or cesium and further employ the required photomultipliertubes (PMT) as detectors. If a linear accelerator (LINAC) is optionallyemployed, then photodiodes and crystals are used in the detector. One ofordinary skill in the art would appreciate how to select a radiationsource type, depending upon his or her inspection requirements.

In one embodiment, where OUI is a large sized container or car thathighly attenuates the X-ray beam, the radiation could be from an X-raytube operating at a voltage in substantial excess of 200 keV, and mayoperate in varying regions, including 450 keV, 3 MeV, 4.5 MeV, and even,but not limited to 6 MeV.

FIGS. 14 and 15 depict a side view illustration and top viewillustration, respectively, of one embodiment of the vehicle of thepresent invention in a folded, or “stowed” position. In this position,the single boom 1401, 1501 detector arrays 1402, 1502 and radiationsource 1403 fold onto the flatbed 1404, 1504 of the vehicle/trailer1405, 1505. Thus, the detector arrays 1402, 1502 and radiation source1403 are preferably positioned in a manner, such that when folded orstored, permit trailer 1405, 1505 to travel safely on public roadways.Additionally, the detectors are preferably integrally formed to enablefor stable, yet rapid deployment. The detectors may also optionally belinear arrays that extend substantially parallel to the base of thetrailer and, when deployed, extend substantially orthogonal to the baseof the trailer.

Referring to FIG. 16, a side perspective view of the single boom cargoscanning system of the present invention in a deployed or “unfolded”position is depicted. In a preferred embodiment, trailer 1601 compriseschassis 1602, having a front face 1603, a rear end 1604, and sides 1605.Trailer 1601 also comprises a trailer (driver's) cab 1610 and a singleboom 1611. In a preferred position, boom 1611 extends centrally abovechassis 1602 from a point (shown as 1612) approximately above rear axle1607, thus allowing it to rotate in the desired directions. Boom 1611has a proximal end attached to the vehicle and a distal end physicallyattached to the radiation source. Boom 1611 preferably consists of ahollow cylindrical main body 1613, a connecting structure 1614, an outerarm 1615, and a telescopic arm 1616. Outer arm 1615 protrudes from theconnecting structure 1614 to preferably form an L-shaped structure. Bothouter arm 1615 and connecting structure 1614 comprise detector panels.

Outer arm 1615 is further connected to telescopic arm 1616. Hydrauliccylinders or actuators (not shown) are provided for the turning movementof boom 1611, outer arm 1615 and telescopic arm 1616. In order tofacilitate push-button deployment and the dispensing away of assemblingtools or skill, the action of folding or unfolding of the outer arm 1615containing the detector array is enabled by a suitable hydraulic systemknown to a person of ordinary skill in the art. One exemplary hydraulicsystem for unfolding the detector panels comprises a reversibleelectrical motor to drive a hydraulic pump that in turn provideshydraulic fluid under pressure to a double acting hydraulic actuatorattached to the trailer. When the hydraulic actuator is required tounfold the detector panel, pressurized hydraulic fluid is pumped intothe chamber, engaging a piston to move a slider ball that in turnunfolds the detector panel. Once the detector panel is unfolded throughan acceptable angle, the detector panel is securely latched in positionusing a mechanical latch such as a simple hook and peg system or anyother latching arrangement known to one of ordinary skill in the art. Asimilar arrangement can be used to deploy the remaining detector panels.

FIG. 17 depicts the top view of the single boom cargo scanning system ofthe present invention, in a partially deployed position. Outer arm 1701is visible and opens, thus making angle 1702 with respect to trailer1703. In a preferred embodiment, the radiation source box (not shown) islocated on the same single boom at the detector boxes (as describedabove), thereby eliminating the need for sophisticated alignment systemseach time the system is deployed. The radiation source is located on oneside of the boom while the detectors are located on the other. Therotating boom allows for the source of radiation to be positionedopposite to the area of the boom supporting the detectors. The radiationsource is permanently fixed in alignment relative to the detector boom.The radiation source is rotated from the storage position to thedeployed position. The electrical power generator is turned on toprovide power to the electrical devices in the system. While thegenerator is deployed, the detectors are unfolded as described above.With the source located on a rotating platform behind the boom post, ashorter boom can optionally be used to enable the requisite distancebetween the source and the detectors. This design also allows forgreater stability, because the position of the radiation source is usedto counterbalance the detector boom.

Referring back to FIG. 16, extension and withdrawal of telescopic arm1616 in relation to the main body 1613 is preferably effectuatedhydraulically using suitable hydraulic cylinders (not shown) in mainbody 1613. Thus, telescopic arm 1616 moves with multiple degrees offreedom. FIG. 18 depicts one exemplary movement of the telescopic arm1801 of the single boom cargo scanning system of the present invention.Telescopic arm 1801 forms an acute angle 1802 with respect to outer arm1803. In FIG. 19, another degree of freedom of the abovementionedtelescopic arm. The telescopic arm 1901 is perpendicular 1902 to theouter arm 1903.

As described in detail above, the detectors preferably comprise panelsthat are capable of being folded, such that, when in a storage position,the detectors recess into the side of the inspection trailer. By formingdetectors such that they can fold in a storage position, it is possibleto produce a compact trailer that can safely, and legally, travelroadways. When unfolded during operation, the detectors assume either alinear or an arched shape.

Now referring to FIG. 20, a rear view illustration of the single boomcargo scanning system of the present invention is depicted. As mentionedabove, connecting structure 2001 and outer arm 2002 consist of detectorarray panels 2003. In a preferred embodiment, the detectors assume anapproximate inverted “L” shape, as they are placed on connectingstructure 2001 and outer arm 2002. The preferred inverted “L” shapedetector enables the radiation source to be closer to the targetvehicle, thus allowing higher penetration capability, and provides forcomplete scanning of the target vehicle without corner cutoff.

At its distal end, the telescopic arm 2005 is attached to radiationsource 2006 and is deployed from boom 2007, once rotated into desiredscanning positions. Single boom 2007 allows for source 2006, positionedat the base of the telescopic arm 2005, to rigidly align with detectorarray 2003.

An array of laser pointers emitting laser radiation is built into thecollimator to facilitate proper alignment of the radiation beam with thedetectors. In one embodiment, optical triangulation method is used foraligning the plane of the radiation beam with a predefined “zero” or“idealized centerline” of the detector system. Such opticaltriangulation techniques, as known to a person of ordinary skill in theart, use a source of light such as a laser pointer to define theradiation beam path. These laser pointers are directed to impinge on apredefined “zero” of the detectors. The “zero” of the detectors may be aspot representing the centroid of the detector system or an idealizedcenterline representing a spatial x-y locus of an ideal fan beam planeintersecting the plane of the detectors substantially orthogonally. Inone arrangement, the spatial position of the laser pointers impinging onthe detectors is sensed by an array of photo-electric diodes of thedetector system that send the corresponding position signals to acomputer housed within the trailer. The computer compares the spatialposition of the laser pointers with a predefined “zero” of the detectorsystem and sends correction control signals to the source box throughthe control cable (attached to the boom) for adjustments until the laserpointers are reasonably lined-up with the detector system.

Radiation source box 2006, attached to telescopic arm 2005, emitspenetrating radiation beam 2008 having a cross-section of a particularshape. Several embodiments for the radiation source, but not limited tosuch embodiments, are described in further detail below. The more rigidalignment of radiation source 2006 with detector array 2003 permits thescanning system of the present invention to operate with a narrower beamwidth and a lower radiation level. Positioning source 2006 at the baseof telescopic arm 2005 also permits a larger field of view relative tothe conventional systems having the source on the vehicle. Also, source2006 can extend as low as six inches off of floor level, shown as 2009,and can provide the under-carriage view 2010 of OUI 2011.

Optionally, boom 2007 deploys and permits detector array 2003 andradiation source box 2006 to extend outward, preferably resting at anangle of about 10 degrees relative to the plane perpendicular to OUI2011. This permits for easy viewing of dense material and hiddencompartments (not shown). The heaviest material in cargo is usuallylocated at the bottom floor of the truck. For example, in one particularembodiment, a linear accelerator (LINAC) is employed. The zero degreecenter point of the beam is the strongest portion of the beam. In orderto capture scans of the floor level of the truck, the radiation sourcebeam is positioned to orientate 15 degrees downward to detect materialsin the undercarriage and then 30 degrees upward to detect the higherportions of the load. This ensures that the strongest X-rays (at thezero degree position or, center of the X-ray tube) are oriented at thefloor level of the truck, which is critical to the performance of thesystem as the densest and most difficult portion of a truck to image isthe floor level.

During the scanning operation, radiation source 2006 and detector array2003 are activated and the scanning trailer is driven over the OUI, suchthat the objects get positioned between the trailer and radiation source2006. In a preferred embodiment, during the scanning operation, thesource and detectors remain stationary and aligned with respect to eachother while mobilized and passed over the OUI. In a preferredembodiment, the motion of the scanner is kept steady and at a constantvelocity. Since, irregularities in the motion of the vehicle may resultin distortions in the scanned image, the motion is preferably made asregular, even and constant as feasible using known control systems suchas by engaging the trailer motor in “auto speed” mode. As described ingreater detail below, the scanning system is manipulated via a closedloop method to automatically correct images for the different speeds ofoperation of the scanning trailer. Such speed control system is acombination of mechanical, electrical, and software design.

Since the source and detector remain in a relative stationary and fixedposition during the scanning process, collimation can be adjusted to anadvantageous minimum such that the fan beam emerging out of thecollimator just covers the detectors. The collimation mechanism employedis preferably a rotating wheel or any other suitable mechanism as knownto the person of ordinary skilled in the art. Referring to FIG. 21, arotating collimation wheel of one embodiment of the present invention isdepicted. Rotating wheel 2101 is used to develop pencil beam 2102, whichpasses through the object. A series of tubular collimators 2103 aredistributed as spokes on rotating wheel 2101. Cross-section of pencilbeam 2102 is substantially rectangular, but is not limited to suchconfigurations. The dimensions of pencil beam 2102 typically define thescatter image resolution, which may be obtained with the system.

As known in the art, X-ray scanning operates on the principle that, asX-rays pass through objects, the radiation gets attenuated, absorbed,and/or deflected owing to a number of different physical phenomena thatare indicative of the nature of the material being scanned. Inparticular, scattering occurs when the original X-ray hits an object andis then deflected from its original path through an angle. These scatterradiations are non-directional and proportional to the total energydelivered in beam path. A narrowly collimated beam will keep the overallradiation dose minimal and therefore also reduce the amount of scatterradiation in the area surrounding the scanner, thereby reducing the“exclusion zone”.

During deployment the inspection trailer is driven to the inspectionsite and the radiation source and detector booms are positioned. Becausethe trailer moves over the OUI, it does not need to be positionedstrategically to allow for high throughput. Rather, the trailer may bedriven over any OUI, located anywhere, given that there is space for theinspection trailer to pass without disrupting port activities. Anotheraspect that may influence the decision of positioning the trailer couldbe the availability of a large enough area, called the “exclusion zone”,around the scanner system. The exclusion zone is an area around thescanner in which general public are not authorized to enter due to thepossibility of their getting exposed to doses of radiations scatteredduring the scanning process. The exclusion area is dependent upon themagnitude of current setting the intensity of the radiation source.

FIG. 22 illustrates a preferred embodiment of the detector array 2201 asemployed in the single boom cargo scanning system of the presentinvention. The detectors 2202 may be formed by a stack of crystals thatgenerate analog signals when X-rays impinge upon them, with the signalstrength proportional to the amount of beam attenuation in the OUI. Inone embodiment, the X-ray beam detector arrangement consists of a lineararray of solid-state detectors of the crystal-diode type. A typicalarrangement uses cadmium tungstate scintillating crystals to absorb theX-rays transmitted through the OUI and to convert the absorbed X-raysinto photons of visible light. Crystals such as bismuth germinate,sodium iodide or other suitable crystals may be alternatively used asknown to a person of ordinary skill in the art. The crystals can bedirectly coupled to a suitable detector, such as a photodiode orphoto-multiplier. The detector photodiodes could be linearly arranged,which through unity-gain devices, provide advantages overphoto-multipliers in terms of operating range, linearity anddetector-to-detector matching. In another embodiment, an area detectoris used as an alternative to linear array detectors. Such an areadetector could be a scintillating strip, such as cesium iodide or othermaterials known in the art, viewed by a suitable camera or opticallycoupled to a charge-coupled device (CCD).

FIG. 23 is a detailed illustration of one preferred embodiment of thedetectors 2300 employed in the detector array 2305, as shown in FIG. 21.The detectors are preferably angled at 90 degrees relative to theradiation source focal point. The radiation scattered from the radiationsource beam is detected by the strategically positioned detectors, thusimproving image quality.

FIG. 24 is a detailed illustration of another preferred embodiment ofthe detectors employed in the detector array shown in FIG. 22, where thedetectors are arranged in a dual row. Detector array 2401 preferablycomprises a dual row of detectors 2402 that are blended together in aninterlacing fashion to allow better resolution using a suitablealgorithm. The focus algorithm provides automatic means to combine theimages resulting from the dual row of detectors 2402, which are athalf-detector offset from each other, into a single row allowing fordouble resolution compared to a single row of detectors. This blendingmethod eliminates jagged edges in the resultant images from the use ofthe two detector rows 2402.

At any point in time when the radiation source is on, the detectors aresnapshots of the radiation beam attenuation in the OUI for a particular“slice” of the OUI. Each slice is a beam density measurement, where thedensity depends upon beam attenuation through the OUI. The radiationdetectors convert the lateral radiation profile of the OUI intoelectrical signals that are processed in an image processing system,housed in the inspection trailer, while the OUI is being conducted pastthe source and the radiation detector.

The X-ray image processing and control system, in an exemplaryembodiment, comprises a computer and storage systems which records thedetector snapshots and software to merge them together to form an X-rayimage of the vehicle which may further be plotted on a screen or onother media. The X-ray image is viewed or automatically analyzed by OUIacquisition system such as a CRT or monitor that displays the X-rayimage of the vehicle to an operator/analyst. Alternatively, the OUIacquisition systems may be a database of X-ray images of desiredtargets, such as automobiles, bricks or other shapes that can becompared with features in the image. As a result of this imaging, onlyarticles that were not contained in the reference image of the containeror vehicle are selectively displayed to an operator/analyst. This makesit easier to locate articles that do not correspond to a referencecondition of the container or vehicle, and then to conduct a physicalinspection of those articles. Also, for high-resolution applications,the electronics used to read out the detector signals may typicallyfeature auto-zeroed, double-correlated sampling to achieve ultra-stablezero drift and low-offset-noise data acquisition. Automatic gain rangingmay be used to accommodate the wide attenuation ranges that can beencountered with large containers and vehicles.

FIG. 25 is a block diagram of an exemplary X-ray image processing anddisplay unit of the single boom cargo scanning system of the presentinvention. X-ray image display and processing unit 2500 includesdetectors 2501 coupled through data processing units (DPU) 2502, drivers2503, interface card 2504 and computing device 2505. Computing device2505 processes discrete photo current integration information receivedfrom the detectors 2501 via interface card 2504, which is attached tocomputing device 2505. Display device 2506, attached to computing device2505, renders the image of the contents of the target object uponreceiving information from computing device 2505. The detector arrayincludes a plurality of detectors. The detectors 2501 are coupled ingroups of data processing circuits (not shown). It is preferred thatthree groups of detectors 2501 are employed, wherein the number ofdetectors 2501 in use is dependent upon the height of the OUI (notshown), and the resolution (i.e. number of pixels) of the image desired.In a preferred configuration, three data processing units 2502 arecoupled to line driver 2503, which is coupled to network interface 2504.Interface 2504, such as but not limited to RS-485, is embodied on acircuit card located within computing device 2505.

Computing device 2505 is preferably a microprocessor based personalcomputer system and operates under the control of a software system.Computing device 2505 thus receives detector pulses 2507 from each ofthe data processing units 2502, in response to the detection ofindividual photons 2508 by the detectors. The software system processesthe incoming detector pulses 2507, evaluates their relative amplitudes(i.e. energies), and generates a radiographic image-like display outputsignal, which is coupled to the graphical display device 2506, thusgenerating a graphical representation of the densities within the OUI.

The present invention generates a graphical representation, i.e., animage, of the densities of the contents of the vehicle under inspection.This allows for easy visual interpretation of the results of thescanning of the OUI.

Advantageously, the preferred software system also causes the display ofa reference image simultaneously with the image generated in response tothe vehicle under inspection, so that an operator of the presentembodiment can easily make a visual comparison between what an object ofthe type being inspected should “look like”, and what the OUI actually“looks like”. Such “side-by-side” inspection further simplifies thedetection of contraband using the present embodiment.

The vertical linear array configuration of the detector array isdesigned to provide a resolution of grid points spaced approximatelyevery 5 cm along the length and about 4.3 cm along the height of thetarget OUI. This resolution is adequate to achieve a detectability limitof less than half a kilogram of contraband per 4.3 cm by 5 cm gridpoint(or pixel). The pixel size can be easily varied by appropriatelyselecting the location of the radiation source and the detectors withinthe detector array, and by varying the distance between inspectionspoints longitudinally (via choice of counting interval and scan speedalong the length of the target vehicle). A suitable algorithm implementsa correction that takes into account the speed of the scanning trailerunder motion, the scanning rate (i.e., number of lines scanned persecond), detector size, and distance between the detectors.

In a preferred embodiment, a closed loop method is employed toautomatically correct images for the varying speeds of operation of thescanning system. The speed control system is a function of mechanical,electrical, and software components of the scanning system of thepresent invention.

Referring to FIG. 26, a flow chart depicts the operational steps of thesingle boom cargo scanning system of the present invention once theimage generation program is executed. In step 2601, the single boomscanning system of the present invention initiates image generation. Instep 2602, movement of the trailer containing the single boom begins. Inanother embodiment, where the OUI is optionally driven underneath andthrough the self-contained inspection system, start-sensors may bestrategically placed to allow an imaging and control system, locatedwithin the inspection trailer, to determine that the OUI cab, in thecase of a vehicle, has passed the area of beam and the vehicle to beinspected is about to enter the X-ray beam position. Thus, as soon asthe vehicle to be inspected trips the start-sensors, the radiationsource is activated to emit a substantially planar fan-shaped or conicalbeam for the duration of the pass) that is suitably collimated forsharpness and made to irradiate substantially perpendicular to the pathof the vehicle.

In step 2603, the detectors are calibrated by irradiation with theradiation source at a point along the track prior to the radiationsource arm and detector array arm reaching the OUI. In other words,calibration occurs before the OUI is interposed between the detectorarray and the radiation source. The irradiation of the detector arraysets a baseline, in step 2604 of radiation (or “white” photo currentintegration level) analogous to a density in the OUI approximately zeroand a maximum photo current integration level. In step 2605, three photocurrent integration measurements are preferably made in this manner foreach detector. In step 2606, measurements are arranged for each detectorand stored in an array having a white level element for each detector.

In step 2607, the horizontal position is set to zero. The horizontalposition corresponds to a position along the scanning track, randomlyselected, at which density measurements are taken for the first time.This horizontal position should be at a point before the OUI isinterposed between the detector array and the radiation source. In step2608, the detector measurement is set to zero, corresponding to thefirst detector in the detector array to be queried for a photo currentintegration level. The detector is queried in step 2609 for a photocurrent integration level and is instructed to restart measurement. Instep 2610, the detector restarts measurement in response to theinstruction to restart. In step 2611, photo current integration leveldetermined in step 2609 is passed to the measurement device. In step2612, the level of photo current integration measured is stored in anarray and is then converted into a pixel value in step 2613. Theconversion is achieved by mapping the amount of photo currentintegration to a color, for display on the display device. In step 2614,the detector number queried is converted into a vertical position on thescreen display. The horizontal position of the radiation source and thedetector array along the scanning track is converted to a horizontalposition on the screen display in step 2615. Once the vertical andhorizontal positions are ascertained, a pixel is illuminated in step2616 using the color corresponding to the photo current integrationlevel.

In step 2617, a determination is made as to whether all of the detectorsin the detector array have been queried for a photo current integrationlevel for the current horizontal position. If all the detectors have notbeen queried, the detector number to be queried is incremented in step2618. The image generation program continues by querying the nextdetector in the detector array for the photo current integration leveland by instructing such detector to restart measurement as in step 2610.The image generation program continues executing from this step, asdescribed in detail above.

If all the detectors within the detector array have been queried for thecurrent horizontal position, the horizontal position is incremented instep 2619. In step 2620, a determination is made as to whether or notthe radiation source arm and the detector array arm of the single boomscanning trailer are still in motion. If the boom components are stillin motion, the detector to be queried is reset to zero and the imagegeneration program continues, as shown in step 2621. If the single boomscanning system has stopped moving, the image generation program isterminated in step 2622.

The above examples are merely illustrative of the many applications ofthe system of present invention. Although only a few embodiments of thepresent invention have been described herein, it should be understoodthat the present invention might be embodied in many other specificforms without departing from the spirit or scope of the invention. Forexample, other configurations of cargo, tires, tankers, doors, airplane,packages, boxes, suitcases, cargo containers, automobile semi-trailers,tanker trucks, railroad cars, and other similar objects under inspectioncan also be considered. Therefore, the present examples and embodimentsare to be considered as illustrative and not restrictive, and theinvention is not to be limited to the details given herein, but may bemodified within the scope of the appended claims.

1. A mobile inspection system for generating an image representation oftarget object using a radiation source, comprising: a foldable boomwhich is configured to physically attach to a vehicle; a first detectorarray housing physically attached to at least one horizontal portion ofthe foldable boom, wherein said first detector array housing contains aplurality of detectors; a second detector array housing physicallyattached to at least one vertical portion of the foldable boom whereinthe second detector array housing contains a plurality of detectors; andat least one source of radiation wherein said radiation source isfixedly attached to at least one vertical portion of said boom andwherein the radiation source and first detector array housing areconfigured to form a beam path and wherein said beam path is skewed atan angle of greater than 90 degrees relative to at least one side ofsaid vehicle.
 2. The system of claim 1 further comprising a hydraulicsystem located in the vehicle to rotate the boom.
 3. The system of claim1 further comprising at least one sensor to determine when a targetobject is positioned between the radiation source and at least one ofthe first or second detector array.
 4. The system of claim 3 wherein thesensor, upon being activated by the movement of a target object,transmits a signal to activate said radiation source.
 5. The system ofclaim 1 wherein at least one vertical portion of the boom has a mainbody physically attached to the vehicle, at least one horizontal portionof the boom has an outer arm physically attached to the main body, andat least one vertical portion of the boom has a telescopic armphysically attached to the outer arm.
 6. The system of claim 5 whereinthe boom has a first configuration and a second configuration.
 7. Thesystem of claim 6 wherein, in said first configuration, the outer armand telescopic arm are positioned in a substantially parallel horizontalalignment with said vehicle.
 8. The system of claim 6 wherein, in saidsecond configuration, the outer arm and telescopic arm are positioned ina substantially perpendicular alignment with said vehicle.
 9. The systemof claim 1 wherein the radiation source is collimated through anadjustable collimator.
 10. The system of claim 1 wherein the radiationsource is aligned with at least one the first or second detector array.11. The system of claim 10 wherein the radiation source is aligned withat least one of the first or second detector array using opticaltriangulation techniques.
 12. The system of claim 1 wherein saiddetectors in at least one of the first or second detector arrays and areangled at substantially 90 degrees relative to a focal point of saidradiation source.
 13. The system of claim 12 wherein said detectors arearranged in a dual row.
 14. The system of claim 13 wherein said dual rowof detectors are configured in an interlacing configuration.
 15. Thesystem of claim 14 wherein data generated by said dual row of detectorsare subjected to imaging processing.
 16. The system of claim 15 whereinsaid imaging processing blends images detected by each of said dual rowsinto a single image. 17-31. (canceled)
 32. The system of claim 1 whereinthe radiation source is an X-ray tube operating in excess o 200 keV. 33.A mobile inspection system for generating an image representation oftarget object using a radiation source, comprising: a foldable boomwhich is configured to physically attach to a vehicle; a first detectorarray housing physically attached to at least one horizontal portion ofthe foldable boom, wherein said first detector array housing contains aplurality of detectors; and at least one source of radiation whereinsaid radiation source is fixedly attached to at least one verticalportion of said boom and wherein the detectors in said first detectorarray housing are arranged in a dual row.
 34. The system of claim 33wherein said dual row of detectors are configured in an interlacingconfiguration.
 35. The system of claim 33 further comprising a seconddetector array housing physically attached to the foldable boom whereinthe second detector array housing contains a plurality of detectorsarranged in a dual row and wherein said dual row of detectors in thesecond detector array are configured in an interlacing configuration.